Boom feet for excavators



Feb. 21, 1933. w LEHMAN ET AL 1,898,453

BOOM FEET FOR EXCAVATORS Filed Nov. 5, 1928 2 Sheets-Sheet l .52 M .54241 231 g ze 5 Fl: H 45 VENTOR5 ATTORNEYS.

Feb. 21, w L HM ET AL 1,898,453

BOOM FEET FOR EXCAVATORS Filed Nov. 3, 1928 2 SheetsSheet 2 IN VEN TORS,

BYMWI'JWW ATTORNEYS.

Patented Feb. 21, 1933 UNITED STATES PATENT OFFICE WERNER LEHMAN ANDMITCHELL L. FYKSE, OF SOUTH MILWAUKEE, WISCONSIN, AS- SIG-NORS T0BUC'YRUS-ERIE COMPANY, OF SOUTH MILWAUKEE, WISCONSIN, A COR- PORATION OFDELAWARE BooM rrJEr ron EXOAVATORS Application filed November 3, 1928.Serial No. 317,088.

Our invention relates to new and useful 1mprovements in boom feet forexcavators.

Power-excavators, and more particularlypower-shovels, are well-known inthe excavating art. They have a main platform, which contains most ofthe machinery. A boom, with its foot pivotedon a horizontal pivot to oneedge of this platform, carries the excavating implements.

It is the principal object of our invention to provide, for such amachine, a more wearresisting boom-foot pivot, and one '"which willintroduce less strains into the boom.

Further objects andadvantages of our invention will be readily evident,as the description progresses.

Theinvention consists in the novel parts, and in the combinations andarrangements thereof, which are defined in the appended claims; and ofwhich one embodiment is exemplified in the accompanying drawings whichare hereinafter particularly described and explained.

Throughout the description, the same reference number is'applied to thesame member or to similar members.

Figure 1 is a horizontal section of part of the platform, with a planview of the foot of the boom and boom braces. I

Figure 2 is a vertical section of the sam part of the platform, with aside elevation of the foot of the boom, all taken along the lines 22 ofFigure 1, with the link removed. v

' Figure 3 is a plan View of one of the boom foot castings.

Figure 4 is a side elevation of said cast- Figure 5 isa plan view of oneof the links which holds the boom foot in place.

- Figure 6 is a side elevation of said link.

Figure 7 is a horizontal section of part of the platform, showing one ofthe pins welded in place. I

Figure 8 is said part, partly in vertical section and partly in sideelevation, showing the pin welded in place, all taken along the lines 88of Figure 7.

Referring to the drawings, it will be seen that 10 is the main platformof an excavator.

Projecting forwardly therefrom are a pair of lugs 11, 12 to hold theright hand brace, a pair 13, 14 to support the right hand boom footcasting, a pair 15, 16 to support the left hand boom foot casting, and apair 17, 18 to hold the-left hand brace. I

' The main structural part 19 of the boom, has riveted at its foot thetwo boom foot castings 20, 21, of each of which a reinforced curvedportion 22 or 23, bears against a pin 24'or 25, which passes through thelugs 13 and 14 or 15 and 16, and is welded in place as at 26 or 27. Thefact that this curved portion 22 or 23 does not completely embrace pin24 or 25 we shall describe in the claims by the word open; Each boomfoot casting also carries, integral therewith, reinforcing webs 48, anda hook 28 or 29, which engages a hold 30 or 31 in a link 32 or 33. Eachsuch link has a hole 34' or 35, which fits over pin 24 or 25, and'isheld in place by acotter-pin (not shown) passing through hole 36 or 37of such pin 24 or 25. The object of the links is to limit the depar tureof the boom foot castings from contact with the pins 24 and 25. Thesepins are made of softer material than the lugs and the boom footcastings, and are readily replaceable, thus taking all the wear. One ofthe linksis shown in Figures 5 and 6, in which 38 represents a roundedportion of the edge of the hole 30, which has been rounded forengagement with the hook 28. 7 Passing through lugs 11 and 12 or 17 and18, is a pin 39 or 40, which is welded in place, as at 41 or 42. Eachsuch pin supports abrace-link 43 or 44, to which is attached one of theboom braces 45 and 46, adjustable as by turnbuckle 47. Each boom bracepasses to an anchorge (not shown) on the side of the boom.

The reason that the pins 24, 25, 39 and 40 are all welded in place is toprevent the pin from rotating and thus grinding the boom foot castingand the lugs, more particularly the latter. Any slight wearing of thecurved portions 22 and 23 of the boom foot castings, can be taken up bythe turnbuckles, The weld on each of the pins extends only aboutone-third ofthe way around and is only about a quarter inch thick. Torenew a pin, the weld would either be chipped away, or softened slightlyby an acetylene torch, the pin being then knocked out.

In the past it has been usual to have rounded points at the foot of theboom stepped into sockets on the platform. Our invention is not a merereversal of the parts of this former device, for the following reasons:

First, our invention causes the boom and the boom braces to rotate aboutthe same axis, when the boom is raised or lowered, thus eliminatingstrains and slack in the braces.

Secondly, in machine shop practice, it is infinitely simpler to alignthe eight holes for the four pins, than to align pockets for seating therounded ends of the two boom footcastings of the prior art. In eithercase, the two boom foot casting can be aligned, without chipping, byadjusting the template for the rivet-holes or bolt-holes (such as 49) tothe pivot point of each casting as at A in Figure 2. Thus the holes ineach casting are adjusted to the concave surface of that casting itself,thus rendering all boom foot castings interchangeable as well asautomatically aligned to all others.

Thirdly, when the swing of the machine is accelerating or decelerating,the moment of inertia of the boom and all that is carried by it, tendsto bend the boom to one side, thus pulling one of its feet out ofengagement with the platform. Our construction permits this movement toa limited degree, thus introducing an element of flexibility int-o theboom foot mounting.

Fourthly, when the swing of the machine is accelerating or decelerating,the moment of inertia of the dipper and contents tends to rotate theouter end of the boom about the lengthwise axis of the boom, thuslifting up one foot of the boom and depressing the other. Ourconstruction permits this movement to a limited degree, thus introducinga further element of flexibility into the boom foot mounting.

Fifthly, this same tendency to rotate the outer end of the boom aboutthe lengthwise axis of the boom tends to bend one leg upward and theother leg downward about a point such as B in Figure 2. This causes ashear stress in the rivets or bolts which fasten the boom foot castings20 and 21 to the main structural part 19 of the boom. This shear stressis proportional to the lever arm from B to A, which is the point ofcontact of the boom foot casting with its support on the main platform.Obviously our construction by reversing the sex of the contacting parts,decreases this lever arm n'iaterially.

The old construction possessed to some extent the third and fourthadvantages above enumerated, but these are retained and augmented by ournew construction. When the former boom was twisted, as aforementioned,the torsion was considerably reduced by one of the boom foot castingsriding up and out from its socket. If we were to have drilled holesthrough our boom foot castings for the pivotal insertion of pins 24 and25, we should have lost this advantage of the old design, and this losswould have greatly olfset the advantages gained by other features of ourinvention. But, by not completing the circle of curve 22 tightly aboutpin 24, and further by giving curve 22 a larger radius than that of thepin, we retain the riding up and out of the old construction, and infact permit even more riding up and out. The double pivot feature of thelinks 32 and 33 permits this riding up and out, while at the same timelimiting the departure of the boom foot from contact with the pins.

Having now described and illustrated one form of our invention, we wishit to be understood that our invention is not to be limited to thespecific form or'arrangement of parts hereinbefore described, except inso far as such limitations are specified in the appended claims.

We claim:

1. In a power excavator, the combination of: a main platform, with fourpairs of forwardly projecting lugs; aligned holes through all eightlugs; four cylindrical pins, one being inserted in each pair of holes,and each pin being removably welded in place; a boom; two boom-footcastings attached thereto, each having a rearwardly open projectingconcave surface, of greater radius than that of the pin, for engagementwith one of the aforementioned pins, each casting also having aforwardly projecting hook; two links, each engaging one of said hooksand one of said pins, for limiting the departure of said concave surfacefrom contact with its pin; means for retaining each link on its pin; andsidewardly projecting adjustable boom-braces, each passing from the boomto one of the other two pins.

2. In a power excavator, the combination of: a main platform, with fourpairs of forwardly projecting lugs; aligned holes through all eightlugs; four pins, one being inserted in each pair of holes; a boom; twoboom-foot castings attached thereto, each having a rearwardly projectingconcave surface, of greater radius than that of the pin, for engagementwith one of the aforementioned pins, and each casting also having aforwardly projecting hook; two links, each engaging one of said hooksand one of said pins, for limiting the departure of said concave surfacefrom contact with its pin; means for retaining each link on its pin; andsidewardly projecting boom-braces, each passing from the boom to one ofthe other two pins.

3. In a power excavator, the combination of: a main platform, with fourpairs of forwardly projecting lugs; aligned holes through all eightlugs; four pins, one being inserted in each pair of holes; a boom; twoboom-foot castings attached thereto, each having a rearwardly projectingopen concave surface, of greater radius than that of the pin, forengagement with one of the aforementioned pins, means for limiting thedeparture of said concave surface from contact with its pin; andsidewardly projecting boom-braces, each passing from the boom to one ofthe other two pins.

4. In a power excavator, the combination of: a main platform, with fourpairs of forwardly projecting lugs; aligned holes through all eightlugs; four pins, one being inserted in each pair of holes; a boom,having two laterally aligned rearwardly projecting concave surfaces, ofgreater radius than that of the pin, each of said surfaces being forengagement with one of the aforementioned pins; means for limiting thedeparture of each of said concave surfaces from contact with its pin;and sidewardly projecting boom-braces, each passing from the boom to oneof the other two pins.

5. In a power excavator, the combination of: a main platform, with twoconvex forwardly upwardly projecting parts; a boom; two boom-footcastings rigidly attached thereto, each having a rearwardly projectingconcave surface, of substantially greater radius than that of the convexpart of the platform, for supporting engagement with one of theaforementioned convex parts of the platform; means closely associatedtherewith, for limiting the departure of said concave and convex partsfrom contact with each other; and sidewardly projecting boombraces, eachpassing from the boom to a pivotal anchorage on the platform, the axesof such anchorages being in alignment with the axis of pivot of theboom-foot.

6. In a power excavator, the combination of: a main platform, with twoconvex forwardly upwardly projecting parts; a boom, having tworearwardly projecting concave surfaces, of substantially greater radiusthan that of the convex parts of the platform, for supporting engagementwith the aforementioned convex parts of the platform; means closelyassociated therewith, for retaining said concave and convex parts inengagement; and sidewardly projecting boom-braces, each passing from theboom to a pivotal anchorage on the platform, the axes of such anchoragesbeingin alignment with the axis of pivot of the boom foot.

7. In a boom-foot casting for excavators, the combination of: a flatplate; reinforcing webs rising from said plate; a forwardly projectinghook, on the outer surface of said plate, to engage a retaining link;and a rearwardly projecting reinforced concave surface, to engagesupportingly a convex projection on the main platform of the machine;said plate being further characterized by containing holes for rivetingor bolting to the boom proper, said holes being located by template withrelation to the point of contact of said concave surface.

8. Boom foot securing means for excavators, comprising: two lugs, on themain frame of the excavator, having aligned holes; a pin, of lesswear-resisting material than the herein-after-referred-to boom foot lugof the excavator, said pin passing through said holes, projectingslightly beyond one of said lugs, and directly removably secured tosuch. lug against rotation with respect thereto, while permitting freerotation of the boom foot about said pin; and a boom foot having arearwardly projecting open lug characterized by a concave rearwardly proecting portion of greater diameter than said pin, for engagementtherewith.

In testimony whereof we afiix our signatures.

WERNER LEHMAN. MITCHELL L. FYKSE.

